Piping systems, such as those used to deliver water to fire suppression sprinkler systems, handle large liquid flow rates under significant pressure. The flow to the sprinkler system is controlled by one or more shut-off valves which may be, for example, slow closing gate valves each operated by a hand wheel turning a jackscrew. Slow closing valves are mandated for sprinkler applications by various specifications, such as those promulgated by Underwriters' Laboratories (UL) or Factory Mutual (FM) to prevent damage upstream of the valve due to the water hammer effect which will occur if a valve is closed rapidly. In pipes carrying high flow rates under significant pressure, the change in momentum caused by a sudden valve closing will generate high transient forces on the pipes which can cause their mountings to fail and the pipe to leak or rupture, thereby rendering the sprinkler system inoperative.
It is desirable to use short throw valves such as quarter-turn ball valves and butterfly valves to control water flow to a sprinkler system due to the simplicity and reliability of such valves. However, these valves are capable of very rapid closing and may cause significant damage to the piping system due to the water hammer effect when manually operated without constraint. To use short throw valves and avoid the water hammer problem, the valves have been modified, for example, by the addition of a multi-turn handle coupled with reduction gearing to prevent quick closing. Such modifications defeat the purpose of using simple quarter turn valves, however, as the modifications render the valves more complicated, more expensive and less reliable. There is clearly a need for a short throw valve that is operable in a manner that avoids the water hammer effect but maintains the simplicity and reliability inherent in such valves.